1. Field of the Invention
This invention relates to environmental temperature controls and more particularly to systems for controlling temperatures in multiple compartment devices.
2. Background Information
The goal of most multiple compartment designs is to quickly and efficiently control the discrete compartment temperatures using one cold air source. This task becomes more difficult when there is a sudden temperature change in a compartment, for example, such as when a refrigerator door is opened and then closed.
Typically refrigerators have a partition that separates the freezer from the fresh food compartment. Refrigerators also have a cold air source, which directs cold air into the freezer. There is typically an aperture in the partition that allows the cold air in the freezer to migrate into the fresh food compartment. A damper selectively covers and uncovers the aperture in the partition to control the amount of cold airflow from the freezer to the fresh food compartment. Refrigerators usually have thermostats that control the cold air source.
One arrangement for controlling refrigerator compartment temperatures is to use a manually controlled damper and a thermostat located in the fresh food compartment. If the temperature in the freezer compartment suddenly increases, the damper will not move, and the cold air source will turn on when the warmer air has migrated from the freezer to the thermostat in the fresh food compartment. A drawback associated with this arrangement is that in most refrigerators, the freezer is located above the fresh food compartment and since heat rises, it could take a significant amount of time before the warmer air migrates down from the freezer to the thermostat in the fresh food compartment. This is especially true if the manual damper was positioned to substantially cover the aperture.
One proposed solution to this problem is to incorporate an automatic damper controller and a thermostat located in the freezer compartment rather than in the fresh food compartment. More specifically, the thermostat would control the cold air source in response to the temperature of the freezer compartment. Also, the automatic damper controller would incrementally control the damper in response to the temperature of the fresh food compartment.
A drawback to this system is that when the freezer compartment is cooled to its set point temperature, the cold air source will shut off, even if the fresh food compartment is warm and has not been sufficiently cooled. The set point temperatures refer to the preset high and low temperature range settings of the compartments. For example, when the air temperature in the fresh food compartment reaches a set point temperature, the cold air source will be either turned on or off. Hence, a need exists for a system which will quickly and efficiently control temperatures in a multiple compartment device in response to compartment temperature changes.